我的二分搜索只会找到位于数组中间的元素

Question

所以我试图进行二分搜索来按姓氏查找，但我的代码只会查找我搜索的元素是否位于数组中间的元素，否则它将冻结并崩溃，有人知道我在做什么吗？做错了吗？谢谢。

      private int binarySearch(string surnameSearched)
    {
        int start = 0;
        int end = direcTable.Length - 1;
        bool found = false;
        bool allListSearched = false;
        int mid = (start + end) / 2;
        while ((!found) && (!allListSearched))
        {
            lvDirectory.Items.Clear();
            if (String.Compare(direcTable[mid].surname, surnameSearched, true) == 0)
            {
                found = true;
            }
            else if (start > end)
            {
                allListSearched = true;
            }
            else if (String.Compare(direcTable[mid].surname, surnameSearched) < 0)
            {
                end = mid - 1;
            }
            else
            {
                start = mid + 1;
            }
        }
        if (found)
        {
            ListViewItem lvi = new ListViewItem();
            lvi.Text = direcTable[mid].extCode;
            lvi.SubItems.Add(direcTable[mid].forename);
            lvi.SubItems.Add(direcTable[mid].surname);
            lvDirectory.Items.Add(lvi);
            return (mid);

        }
        else
        {
            return -1;
        }

Answer 1

       while (start < end)
       {
           int mid = start + (end - start) / 2;
           lvDirectory.Items.Clear();
           if (String.Compare(direcTable[mid].surname, surnameSearched, true) == 0)
           {
               found = true;
           }
         
           if (String.Compare(direcTable[mid].surname, surnameSearched) < 0) // I Dont know on what bases your comparing in this If statment
           {
               end = mid ;
           }
           else
           {
               start = mid + 1;
           }
       }